Control mechanism



June 14, 1949.

Filed Dec. 27, 1945 2 Shets-Sheet 1 mm m H L m m m 6N T.

June14, 1949. A. K. GAYLORD- 2, 3

CONTROL MECHANISM Filed Dec. 27, 1945 2 Sheets-Sheet 2 A TTOZQNEYPatented June If}, 1949 UNITED STATES-- PATENT OFFiCE CONTROL MECHANISMAsa K. Gaylord, Portland, Oreg.

Application December 27, 1945, Serial No. 637,350

Claims. 1

This invention relates to an electrical control mechanism, and hasparticular reference to a novel mounting for a gang of control switchesfor performing sequential switching operations in a predetermined order.

The general object of the invention is to provide a novel mounting meansfor a plurality of individual switches to cause them to make and breakcircuits in a. predetermined order.

Another object is to provide an improved mercury switch mounting havingconcealed wiring to present a neat and clean appearance and to preventtamperin therewith by unauthorized persons.

Another object is to provide an improved rotary control mechanismadapted to be driven by a motor for performing successive switchingoperations at predetermined time intervals.

Another object isto provide an improved smp controller of simplified andeconomical construction for circuits involving a considerable amount ofpower to exert a modulating control over such circuits in relativelysmall increments of power, and to prevent sudden changes involving alarge load.

These and other objects are accomplished in a control mechanismcomprising a hollow insulating mounting tube or drum carrying aplurality of mounting clips for individual switches on its exteriorsurface. The tube is mounted at its ends for rotation in suitablebearings, and is preferably driven at a slow constant speed by anelectric motor through appropriate reduction gearing. The electric motormay operate as a servo-motor .in a control system where the motor movesthe mounting tube back and forth to difierent positions within a rangeof tube rotation less than 360 degrees "in answer to demands from somecondition responsive device. The invention is particularly suited forexerting a modulating control over the heat output of abank of electricheating units in response to demand from a thermostat mechanism whichcauses the motor to assume difierent positions in accordance with thetemperature of the space being heated. The control system for producingoperation of the motor in this manner forms no part .of the presentinvention, nor do the particular circuits in which the mercury switchesare included, the present invention being concerned only with themechanical construction of the control mechanism as exemplified in thepreferred embodiment illustrated in the accompanying drawings.

The supporting clips for the switches are mounted on the rotatableinsulating tube at angular intervals defining stations or control stepsfor the system which is controlled thereby. The invention utilizes acharacteristic feature of conventional mercury tube switches wherebythey eiiect a quick and clean make or break, even when tilted with avery gradual movement from one position to another. Therefore, as themounting tube is slowly rotated in the proper direction the mercuryswitches will slowly be tilted so that as one after another reaches itscritical position it will be caused to make or break a circuit, as thecase may be, without arcing or burning the contacts as would be the casewith switches having solid metal movable contact elements. Although theaction of the mercury in the switch tubes produces in efiect a certainamount of lost motion between the make and break positions in any givenswitch tube, the make position is always the same and the break positionis always the same, so that when rotation of the mounting tube in agiven direction is halted in a predetermined position, the same circuitconnections will invariably be established. The exact angular positionin which the mounting tube comes to rest is, however, not critical,inasmuch as there is a mounting tube rotation corresponding to theangular spacin of the switch tube clips between successive switchingevents. In any intermediate position of the mounting tube, between itslimits of movement, certain of the switches will be definitely off andothers will be definitely on, so that there are no positions which mustbe passed over quickly or by a continuous motion as in streetcarcontrollers or the like. For this reason, it is not necessary to provideindexing mechanism to stop the rotation'of the mounting tube inpredetermined positions with relation-to the stations at which theswitch tubes are mounted, and the driving motor may .be allowed to findits rest position after each movement solely in accordance with thedemand of the condition responsive device. As a matter of fact, in theoperation of a system of this kind, there may be many small movements ofthe mounting tube which are insufficient to produce .55 would beaffected.

The space within the mounting tube is utilized to contain the wiringconnections for the switch tubes. The wires from each switch tube aretrained out through the remote end of the mounting tube to makeavailable the greatest possible length of wire for twisting toaccommodate the range of rotation of the mounting tube. The maximumrotation of the mounting tube between end limits being usually less than180 degrees in modulating controls of the type hereinabove described,and the normal rotation thereof being only a few degrees at a time, nosevere stress is imposed upon the wires to cause them to break or kink.All the wires leaving the switching device are thereby protected andconcealed where they cannot be tampered with.

In the drawings:

Figure 1 is a plan view of a control mechanism embodying the principlesof the present invention;

Figure 2 is an enlarged sectional View showing the construction androtatable mounting of the driving end of the mounting tube;

Figure 3 is a sectional View, taken on the line 3-3 of Figure 2;

Figure 4 is a sectional view similar to Figure 2, showing theconstruction and mounting of the other end of the mounting tube;

Figure 5 is a fragmentary View showing a mounting clip and terminals forone of the mercury switches;

spacing of the successive stations on which the mercury switches aremounted;

Figure 9 is a developed View of the mounting tube showing the stationsat which the mercury switches are mounted;

Figure 10 is a side view of the mounting tube without the switches,showing the manner of securing the removable closure in place; and

Figure 11 is a detail view in section showing a securing means for theremovable closure in the mounting tube.

In the illustrated embodiment of the invention the reference numeraldesignates a hollow mounting tube of suitable rigid insulating materialcarrying a plurality of clips 2| for securing individual switchinginstrumentalities such as v mercury switch tubes 22 angularly spaced ata series of stations to operate in sequence when the tube 20 is rotated.The ends of the tube 20 are mounted for rotation in suitable bearings inhollow brackets 23 and 24 or other supporting members convenientlyarranged on the apparatus to be controlled. These brackets also serve aswiring gutters for containing bundles of wires 25 and 26 leading intothe tube 23 for 2 internal connection with the terminals of the mercuryswitches. In the present embodiment the tube 23 is connected with ashaft 28 on a modulating motor 29 for exerting modulating control over asystem of circuits in the general manner hereinabove described. Figure Iillustrates this general arrangement, it being understood that most ofthe mounting clips and wiring connections are omitted for clearness.

Figures 2 and 3 illustrate the manner in which the driving end of thetube 20 is mounted in the bracket 23 for connection with the shaft 28and the flexible disposition of the wires 25. The bearing for the tube20 may take various forms depending upon the nature of the bracket 23 inthe particular installation. In the present arrangement the bearingcomprises two segmental bearing elements 30 and 3| each extending halfway around the tube and supplementing the other to constitute a fullcircular hearing. The element 3| is a semi-circular strip of fiber orlike material secured to a side wall of the bracket 23 by means of bolts32, the walls of the bracket being cut away at 33 to avoid contact withthe tube. The bearing element 30 may comprise a semi-circular loop ofsheet metal, or other material of which the bracket is made, formed to acylindrical shape to fit the tube and hold it properly seated in thesegment 3|. A disc 34 secured in the tube by means of screws 35 isadapted to receive bolts or rivets 36 securing a flange 3'! on the shaft23 for rotating the tube. An opening 38 extending about threequarters ofthe way around the tube communicates with the interior of the bracket 23for admitting the wires 25 to the interior of the tube in its difi'erentrotative positions. The bearing elements may, of course, be located onthe other side of the opening 38, or the opening 38 may be eliminated byenclosing the extreme end of the tube within the bracket 23 so that thewires 25 may be brought out of the end instead of the side of the tube.

The bearing supporting the other end of the tube 20 is illustrated inFigure 4. Here a full circular bearing ring 40 of fiber or suitable wearresistant material completely surrounds the tube, and is secured byscrews 39 to a vertical wall of the bracket 24 just inside a circularopening 4| through which the tube passes without fric- 40 tionalcontact. In this arrangement the end of the tube opens into the hollowinterior of the bracket 24 to provide access for the wires 26. Thisbearing arrangement may also be used for the driving end of the tube byproviding for passage of the wires 25 through the disc 34. To this end,the disc 34 might be entirely eliminated by providing an external ringgear or the like for rotating the tube.

In order to provide a maximum twisting length for the wires, they areled out from each switch through the remote end of the tube. The wires26 coming in through the right bracket 34 are connected with mercuryswitches on the left end of the tube, and the wires 25 coming in throughthe left bracket 23 are connected with mercury switches on the right endof the tube. The connections for the mercury switches near the center ofthe tube may then be led out the end having the fewest wires. Thus thetwisting lengths of all the wiring connections are considerably longerthan the flexible connections ordinarily used on mercury switches, so aspractically to preclude the possibility of mechanical failure of thewires from twisting stresses, and to reduce the load on motor 29 to aminimum.

The mounting of the mercury switches and their terminals is shown inFigures 5 to '7. Each clip 24 is secured transversely on the outersurface of the mounting tube 20 by means of a bolt 45 having its headwithin the tube and a nut 46 on the outside of the tube. In this way themercury switches may easily be mounted in definite positions or stationsat predetermined angular intervals on the'tube 20 by drilling a singlehole desigteam hated generally at 41 at the proper oint to receive thebolt 45 for each clip.

Adjacent each clip 2 I there are mounted a number of terminals 48 inaccordance with the number of wires 49 on the mercury switch tube usedin that particular clip. However, when connections are made betweendifferent switch tubes, they may be soldered together exteriorly oi themounting tube without the use of. terminals. Each terminal 48 comprisesa bolt having a head 50 which is disposed within the tube 20 so that apair of nuts 5| may be applied to the outer end for securing theterminal in the wall of the tube and for engaging the end of the wire49. The head 50 is preferably of hexagon or other angular shape so thatit may be held or turned by a suitable tool in tightening the nuts 5i,After the terminals ifi have been mounted in the tube and the wires 49connected therewith the internal wiring connections may be made. Thehead 50 is enlarged in the manner shown so that it can be tapped toreceive a screw 52, and this screw is then tightened on the ends of theproper wires within the tube without loosening the nuts 5|. In Figure 6the switch tube 22 is the first switch tube at the left end of themounting tube 20 and so the internal connections comprise certain of thewires 26, leaving the right end of the mounting tube.

Access for tightening the various bolts and screws in the tube 20 formounting the parts and connecting the wires is had by the provision of aremovable panel 55. The panel 55 may cut out in different Ways and indifferent shapes depending upon the size and material of the tube 20 andthe extent of its surface embraced by the mercury switches mountedthereon. In the present embodiment the panel 55 is cut out of the tube20 to substantially the configuration and proportions shown by means ofa band saw so as to leave an opening 58 as shown in Figure 9, having alength and width sufficient for convenient access to all the screws andbolts mounting the clips 2| and the wiring connections. After allinternal wiring connections have been completed, this panel may besecured in place by screws 56 engaging small plates or strips 57 atseveral points as shown in Figures 10 and 11,

It is also within the scope of the invention to bring the wiringconnections out through open-' ings in the mounting tube 20 adjacenteach switch for direct connection therewith so as to make the terminals48 unnecessary. In such case the bolts 45 may be replaced by screws orother mounting means which may be tightened from the outside of themounting tube so as to make the removable panel 55 unnecessary. It isfurther within the scope of the invention to mount the switch tubeswithin the mounting tube.

The mounting tube 20 may be rotated by any suitable means to perform therequired switching operations but it is particularly intended foroperation by a modulating motor 29 having a reduction drive which isadapted to rotate intermittently at a slow constant speed between endpositions embracing a total range of movement of approximately 160. Toexert a modulating control within this range of movement, an operatingrange comprising slightly less than the complete range of movement isdivided up into equal parts in accordance with the number of controlsteps desired. Thus in the present embodiment there are thirteen controlsteps spaced twelve degrees apart to cover a modulating range 6 of 144around thetube 20, as shown in Figure 8. If the tube may rotate throughbetween its 'end positions, an end zone of 8 may then be allowedapproaching each end position of the shaft to insure the turning on ofthe last switc and the turning 011* of the first switch.

The numerals l to I3, therefore, represent stations on the mounting tubeat which switch tubes are mounted, and the angular spacing between thesestations determines the amount of rotation of the tube 2i) betweensuccessive switching events. On a development of the mounting tube asshown in Figure 9, these stations appear as lines for locating centersfor the holes 47. Switching events may be produced in any number and atintervals scheduled in a coordinated program to produce a desiredcooperation between difierent instrumentalities. Thus, in thisembodiment, there is a series of the mounting holes '41 located onalternate ones of the stations I to l3, beginning with station I andending with station [3, this particular series of mountin holes beingidentified in Figure 9 by the numeral 6E3. There is also a series ofmounting holes identified by the numeral 6i located on every stationexcept station I. Mercury switches mounted in the holes 6i may be usedin an electric furnace or like control system to exert a modulating heatcontrol in twelve steps from a minimum heating step to amaximum heatingstep. A variable speed blower may then have its operation coordinatedwith the heat output by a program of switching events produced bymercury tube switches mounted in the holes 6E1. In the illustratedarrangement the blower would start at its lowest speed on station I andthe lowest output heating step would be energized on station 2. Station3 would energize the second heating. step and the second speed of theblower, and thereafter the blower would increase in speed at every otherstation, or each alternate heating step, until at station l3 the blowerwould operate at full speed and the heating units would produce maximumheat output.

The invention, however, is not limited to any particular arrangement ornumber of mercury switches. The foregoing example of one use to whichthe present control mechanism may be put is described merely for thepurpose of illustrating an advantageous application of the invention andis not intended in any way as a limitation on the invention. Any systemof electrical circuits, in addition to or in lieu of heating and fancircuits, may be controlled by this switching device, and

any number of switch tubes may be employed by choosing suitabledimensions for the mounting tube 20. The operation of successiveswitches may be scheduled at intervals either closer together or fartherapart than 12 degrees and also at irregular intervals, and the drivingagency for the tube 29 need not necessarily operate at a constant speednor within the particular range of movement specified. Also, theinvention is not limited to the use of mercury switches as any othertype of switch capable of being carried by the mounting tube 20 andactuated by the rotation thereof may be employed.

Various other changes may be made in the construction and arrangement ofparts in the rotatable mounting of the tube 20 and in the drivinginstrumentality therefor, and all such modifications within the scope ofthe appended claims are included in the invention.

Having now described my invention and in what manner the same may beused, what I claim as new and desire to protect by Letters Patent is;

l. A switching device comprising a hollow tubular member mounted forrotation in bearing means, a plurality of switches mounted on saidvmember for operation by the rotation of said twisting length for thewires within the tubular member sufficient to accommodate a relativelylarge angular movement of the tubular member without damaging the wiresand without imposing an appreciable torque load on the tubular member.

2. A switching device comprising a hollow tubular member mounted at itsends in bearing means for rotation, a plurality of switches mounted onsaid member for operation by the rotation of the member, and flexiblewires extending longitudinally through the interior of said member fromeach switch to an end of the member, the wires from each switch near anend of the member extending to the more remote end of the member toprovide a long twisting length for all the wires within said member.

3. A switching device comprising a hollow tubular member mounted forrotation in bearing means, a plurality of switches mounted on saidtubular member for operation by the rotation of said member, flexiblewires extending longitudinally through the interior of said member fromeach switch to an end of the member at sufiicient distance from theswitch to provide a long twisting length for the wires within themember, and

hollow mounting means for said bearing means to support said device andenclose said wires where they leave said tubular member.

4. A switching device comprising a hollow tubular member mounted forrotation, a plurality of clips at difierent stations on said member formounting switches to be operated by the rotation of the member, a pairof terminals on said member adjacent each clip and having terminalconnections within said member, flexible wires connected with each pairof terminals within said member and extending longitudinally through theinterior of said member to an end thereof sumciently remote from saidterminals to provide a long twisting length for the wires, and anopening in said member to provide access to said interior connections.

5. A switching device comprising a hollow tubular member, a pair ofhollow supports having bearing means receiving the ends of said memberto mount said member for rotation on its longitudinal tubular axis, aplurality of switches mounted at difierent stations on said member foroperation by the rotation of said member, and flexible wires extendinglongitudinally through the interior of said member from each switch toan end of the member at sufficient distance from said switch to providea long twisting length for the wires, said wires thereby extendingthrough said bearing means and being enclosed within said hollowsupports.

ASA K. GAYLORD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,701,398 Vickery Feb. 5, 19291,754,494 Anderson et al Apr. 15, 1930 1,852,539 Ross Apr. 5, 19322,274,558 Murray Feb. 24, 1942

